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Ona Tampa Ocala Venus DeLand Venice Bartow Ruskin Brandon Parrish Palatka Tavares Orlando Seville Placida Dunedin Bronson Gardner Arcadia Sebring Sarasota Lorraine Bushnell Oklawaha Leesburg Lakeland Mulberry Pineland Suwannee Palmdale La Belle Basinger Wauchula Englewood Bradenton Chiefland Inverness Homosassa Kissimmee Polk City Davenport Dade City Avon Park Fort Myers Clearwater Cross City Fort McCoy Rock Ridge Plant City Fort Ogden Frostproof Lake Wales Fort Meade Cape Coral Punta Gorda Myakka Head Myakka City Saint Cloud Lake Alfred Citrus Park Zephyrhills San Antonio Brooksville Port Richey Gainesville Lake Placid Winter Haven Daytona Beach Fort Lonesome Crystal River Tarpon Springs Port Charlotte St. Petersburg Altamonte Springs STARKEY DUNEDIN CROSS BAR RANCH BELLEAIR CYPRESS CREEK MORRIS BRIDGE SOUTH CENTRAL NW HILLSBOROUGH DISPERSED EAST LAKE VERNA ELDRIDGE WILDE NORTH PASCO ODESSA COSME SOUTH PASCO LAKELAND SECTION 21 PINE ISLAND SOUND C H AR L O TT E H A R B O R C A LOO S AHAT C H E E R I V E R LAKE OKEECHOBEE S h e l l Cr e e k Prairie Creek Horse Creek Peace River Big Slough Canal Deer Prairie Creek Myakka River LAKE ISTOKPOGA Lake Jackson Lake Placid Lake June in Winter Br a den River M a n at ee River Litt l e M a n a te e Riv er S. Prong Reedy Lake Lake Livingston Lake Clinch Crooked Lake Buffum Lake P e a ce R i v e r Lake Arbuckle Lake Wechyokapka Lake Rosalie Tiger Lake LAKE KISSIMMEE Lake Marian TAMPA BAY HILLSBOROUGH BAY OLD TAMPA BAY Alafia River N. Prong Lake Hancock Lake Garfield Lake Pierce Lake Jackson Cypress Lake Lake Gentry Alligator Lake Lake Preston East Lake Tohopekaliga Lake Hart Lake Tohopekaliga Lake Conway Lake Hamilton Lake Marion Lake Juliana Lake Mattie Lake Parker Lake Thonoiosassa Blackwater Creek River H i l l s bo ro ug h W ith l a c o o c h e e R iv e r Lake Tarpon A n c l o t e River Pithlachascoiee River Crews Lake Lake Monroe Lake Jessup Lake Harney LAKE APOPKA LAKE HARRIS Lake Dora Lake Griffin Lake Eustis Lake Dorr Lake Norris Lake Weir Lake Panasoffkee Wekiva River Lake Louisa Lake Minnehaha TSALA APOPKA LAKE Crystal River Springs Group LAKE GEORGE Lake Woodruff Lake Disston Lake Kerr ST. JOHNS RIVER Oklawaha River Orange Lake Lake Stafford CRESCENT LAKE Lochloosa Lake Newmans Lake ST. JOHNS RIVER Wekiva River River Waccasassa G U L F O F M E XI C O ATLANTIC OCEAN Lithia Springs Sulphur Springs Rainbow Springs Homosassa Springs WeekiWachee Springs Warm Mineral Springs Chassahowitzka Springs Crystal Springs LEE POLK LAKE DIXIE TAYLOR HENDRY GLADES ORANGE CITRUS MARION PUTNAM DE SOTO OSCEOLA VOLUSIA FLAGLER ALACHUA SARASOTA SEMINOLE ST JOHNS CHARLOTTE HIGHLANDS GILCHRIST OKEECHOBEE PASCO HARDEE SUMTER MANATEE PINELLAS HERNANDO HILLSBOROUGH LEVY 4 5 4 3 1 4 3 4 7 4 7 7 9 6 5 6 1 4 3 2 2 1 2 2 8 6 8 8 1 2 3 4 0 6 2 9 3 3 5 3 5 2 6 7 8 7 8 8 8 5 4 9 8 8 8 5 6 5 5 9 2 1 8 7 6 9 9 3 3 4 9 1 9 47 21 24 44 18 19 10 54 20 53 52 52 45 54 45 52 52 50 25 48 44 43 16 46 16 46 44 11 11 43 49 43 43 45 39 24 17 37 43 46 34 45 35 54 35 38 18 42 47 27 46 31 71 53 17 36 46 42 49 55 48 16 55 13 45 43 44 14 47 50 19 38 52 48 42 12 27 33 37 49 53 48 53 57 38 51 49 42 38 28 20 65 43 21 39 12 49 18 51 13 55 50 40 34 67 40 33 42 67 40 71 54 17 16 40 21 61 21 55 38 59 79 83 78 60 82 45 50 80 81 39 44 22 82 63 34 22 82 88 24 26 23 81 60 78 18 11 19 93 54 11 63 71 15 18 49 15 59 10 96 14 37 99 98 13 67 34 68 52 10 10 26 16 25 75 39 88 41 74 48 48 61 35 50 83 52 39 74 65 86 73 68 51 94 91 81 47 54 98 66 35 85 57 64 35 35 36 66 68 73 46 90 43 77 41 37 56 47 46 61 40 49 60 42 52 50 71 68 43 57 59 48 80 44 81 46 63 43 44 70 46 48 42 47 46 48 48 47 50 47 64 42 18 48 14 51 45 43 77 72 16 75 61 30 19 47 11 10 32 14 14 36 12 16 14 25 39 24 61 42 25 58 57 59 67 25 53 75 69 68 70 87 55 31 67 54 73 66 55 68 90 37 65 44 44 29 61 35 81 72 78 39 66 57 72 59 51 61 96 48 85 20 29 18 44 45 47 19 14 40 93 27 55 71 53 44 88 44 32 32 28 20 27 28 19 96 98 23 47 96 38 17 27 39 96 89 93 15 12 25 48 16 94 11 86 67 80 67 11 78 79 78 -5 27 12 10 65 66 -1 33 13 11 82 28 -3 16 61 48 20 74 50 12 59 -7 78 -7 14 -5 42 36 15 13 14 46 17 58 10 39 14 16 20 43 46 39 40 67 46 47 49 21 36 46 27 35 34 24 29 31 23 27 48 29 19 32 42 38 40 22 48 22 46 27 48 28 23 40 53 44 100 115 103 110 116 109 104 124 127 126 103 126 128 127 118 120 111 114 102 8 6 7 27 35 17 48 31 17 18 29 30 40 50 10 60 70 80 90 0 100 110 120 30 50 60 70 80 90 50 60 70 20 60 50 50 50 70 10 20 30 40 50 60 70 40 70 80 10 50 40 80 50 40 10 20 10 10 70 40 10 30 50 81° 81° 82° 82° 83° 83° 84° 84° 29° 29° 28° 28° 27° 27° SCALE 1:500,000 MILES KILOMETERS 5 0 5 10 15 20 5 0 5 10 15 20 AT L A N T I C OC E A N G UL F O F M E XI C O STUDY AREA MAP AREA ALABAMA GEORGIA FLORIDA U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Prepared in cooperation with the SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT Scientific Investigations Map 3139 Ortiz, A.G., 2010, Potentiometric surface of the Upper Floridan aquifer, west-central Florida, May 2010 POTENTIOMETRIC SURFACE OF THE UPPER FLORIDAN AQUIFER, WEST-CENTRAL FLORIDA, MAY 2010 By A.G. Ortiz Base from Southwest Florida Water Management District digital data, 1992, State Plane Florida East projection, NAD83 Copies of this map can be purchased from: U.S. Geological Survey Branch of Information Services Box 25286 Denver, Colorodo 80225-0286 Figure 1. Change in potentiometric surface of the Upper Floridan aquifer from May 2009 to May 2010 in west-central Florida. Positive values indicate an increase in water-level altitudes. Negative values indicate a decrease in water-level altitudes. HYDROLOGIC CONDITIONS IN WEST-CENTRAL FLORIDA The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by the middle confining unit. The middle confining unit and the Lower Floridan aquifer in west-central Florida generally contain highly mineralized water. The water-bearing units containing fresh water are herein referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is the principal source of water in the Southwest Florida Water Management District and is used for major public supply, domestic use, irrigation, and brackish water desalination in coastal communities (Southwest Florida Water Management District, 2000). This map report shows the potentiometric surface of the Upper Floridan aquifer measured in May 2010. The potentiometric surface is an imaginary surface connecting points of equal altitude to which water will rise in tightly-cased wells that tap a confined aquifer system (Lohman, 1979). This map represents water-level conditions near the end of the dry season, when groundwater levels usually are at an annual low and withdrawals for agricultural use typically are high. The cumulative average rainfall of 55.21 inches for west-central Florida (from June 2009 through May 2010) was 2.55 inches above the historical cumulative average of 52.66 inches (Southwest Florida Water Management District, 2010). Historical cumulative averages are calculated from regional rainfall summary reports (1915 to most recent complete calendar year) and are updated monthly by the Southwest Florida Water Management District. This report, prepared by the U.S. Geological Survey in cooperation with the Southwest Florida Water Management District, is part of a semi-annual series of Upper Floridan aquifer potentiometric-surface map reports for west-central Florida. Potentiometric- surface maps have been prepared for January 1964, May 1969, May 1971, May 1973, May 1974, and for each May and September since 1975. Water-level data are collected in May and September each year to show the approximate annual low and high water-level conditions, respectively. Most of the water-level data for this map were collected by the U.S. Geological Survey during the period May 17-21, 2010. Supplemental water-level data were collected by other agencies and companies. Most water-level measurements were made during a 5-day period; therefore, measurements do not represent a "snapshot" of conditions at a specific time, nor do they necessarily coincide with the seasonal low water-level condition. WATER-LEVEL CHANGES Water levels in about 96 percent of the wells measured in May 2010 were higher than the May 2009 water levels (Ortiz, 2009). Data from 412 wells indicate the May 2010 water levels ranged from about 4 feet below to about 22 feet above the May 2009 water levels (fig. 1). The largest water level increases occurred in southwest Polk County and over a large extent of Hardee County. The largest water level decline occurred in northwest Highlands County (fig. 1). Water levels in about 79 percent of the wells measured in May 2010 were lower than the September 2009 water levels (Ortiz, 2010). Data from 404 wells indicate the May 2010 water levels ranged from about 25 feet below to 5 feet above the September 2009 water levels. The largest water level decline was in north-central Manatee County and the largest rise in water levels was in northwest Pasco County. ACKNOWLEDGMENTS The author thanks Tampa Bay Water and CF Industries for their assistance with the collection of data used to prepare this report. SELECTED REFERENCES Lohman, S. W., 1979, Ground-water hydraulics: U. S. Geological Survey Professional Paper 708, 72 p. Ortiz, A. G., 2009, Potentiometric surface of the Upper Floridan aquifer, west-central Florida, May 2009: U.S. Geological Survey Scientific Investigations Map 3093, 1 sheet. Ortiz, A. G., 2010, Potentiometric surface of the Upper Floridan aquifer, west-central Florida, September 2009: U.S. Geological Survey Scientific Investigations Map 3117, 1 sheet. Southwest Florida Water Management District, 2000, Aquifer characteristics within the Southwest Florida Water Management District: Broooksville, FL, 123 p. Southwest Florida Water Management District, 2010, Hydrologic conditions for the month of May 2010: Broooksville, FL, 84 p. EXPLANATION MUNICIPAL WELL FIELD POTENTIOMETRIC CONTOUR -- Shows altitude at which water would have stood in tightly cased wells. Contour interval is 10 feet. National Geodetic Vertical Datum (NGVD) of 1929. Hachures indicate depressions. Dashed where approximately located. BOUNDARY OF SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT OBSERVATION WELL -- Number is altitude of water level in feet above or below NGVD of 1929. SPRING CITY OR TOWN OBSERVATION WELL -- Number is altitude of water level in feet above or below NGVD of 1929. Bold number indicates water levels corrected for salinity. VERNA 20 16 21 4.99 to -0 >0 to 4.99 5.00 to 9.99 10.00 to 14.99 15.00 to 19.99 >=20.00 EXPLANATION Change in the potentiometric surface, in feet (Positive values indicate an increase in water-level altitudes)
